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  • Meteorology and Climatology  (1)
  • Paleoclimate  (1)
  • 130-806; AGE; Alkenone, unsaturation index UK37; Alkenones; COMPCORE; Composite Core; Joides Resolution; Leg130; North Pacific Ocean; Pliocene; Sea surface temperature, anomaly; SST
  • 167-1021; AGE; Alkenone, unsaturation index UK37; Alkenones; COMPCORE; Composite Core; Joides Resolution; Leg167; North Pacific Ocean; Pliocene; Sea surface temperature, anomaly; SST
  • 2010-2014  (2)
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  • 1
    Publication Date: 2019-07-13
    Description: Both North and East Africa experienced more humid conditions during the early and mid-Holocene epoch (11,000-5000yr BP; 11-5 ka) relative to today. The North African Humid Period has been a major focus of paleoclimatic study, and represents a response of the hydrological cycle to the increase in boreal summer insolation and associated ocean, atmosphere and land surface feedbacks. Meanwhile, the mechanisms that caused the coeval East African Humid Period are poorly understood. Here, we use results from isotopeenabled coupled climate modeling experiments to investigate the cause of the East African Humid Period. The modeling results are interpreted alongside proxy records of both water balance and the isotopic composition of rainfall. Our simulations show that the orbitally-induced increase in dry season precipitation and the subsequent reduction in precipitation seasonality can explain the East African Humid Period, and this scenario agrees well with regional lake level and pollen paleoclimate data. Changes in zonal moisture flux from both the Atlantic and Indian Ocean account for the simulated increase in precipitation from June through November. Isotopic paleoclimate data and simulated changes in moisture source demonstrate that the western East African Rift Valley in particular experienced more humid conditions due to the influx of Atlantic moisture and enhanced convergence along the Congo Air Boundary. Our study demonstrates that zonal changes in moisture advection are an important determinant of climate variability in the East African region.
    Keywords: Meteorology and Climatology
    Type: Lamont Contribution No. 7467 , GSFC.JA.5113.2011 , Earth and Planetary Science Letters; 307; 2-Jan; 103-112
    Format: text
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  • 2
    Publication Date: 2022-05-25
    Description: Author Posting. © The Author(s), 2012. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Climate Dynamics 41 (2013): 1291-1306, doi:10.1007/s00382-012-1483-0.
    Description: High-resolution sedimentary paleoclimate proxy records offer the potential to expand the detection and analysis of decadal- to centennial-scale climate variability during recent millennia, particularly within regions where traditional high-resolution proxies may be short, sparse, or absent. However, time uncertainty in these records potentially limits a straightforward objective identification of broad-scale patterns of climate variability. Here, we describe a procedure for identifying common patterns of spatiotemporal variability from time uncertain sedimentary records. This approach, which we term Monte Carlo Empirical Orthogonal Function (MCEOF) analysis, uses iterative age modeling and eigendecomposition of proxy time series to isolate common regional patterns and estimate uncertainties. As a test case, we apply this procedure to a diverse set of time-uncertain lacustrine proxy records from East Africa. We also perform a pseudoproxy experiment using climate model output to examine the ability of the method to extract shared anomalies given known signals. We discuss the advantages and disadvantages of our approach, including possible extensions of the technique.
    Description: JET acknowledges the UCAR Climate and Global Change Postdoctoral Fellowship for support.
    Description: 2014-08-26
    Keywords: Paleoclimate ; Africa ; Empirical orthogonal functions ; Monte Carlo ; Uncertainty ; Geochronology
    Repository Name: Woods Hole Open Access Server
    Type: Preprint
    Format: application/pdf
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